When Steve extends the bowl of candy to Sam, all of the candy is below the top pf the bowl. However, when Sam takes some candy, he takes a candy bar that is sticking up out of the bowl.
At one scene the old man gets glass splinter in his hands, and are unable to hold the shotgun or close the door, but then as soon as the first attack is over the cuts on his hands suddenly disappear; he is now able to slam the window for help, grab the shotgun and perform shooting etcetera without any harm.
Sam's burlap mask goes from the mouth being sewn to unsewn back to being sewn throughout the end of the movie.
When Mr. Kreeg gets his Achilles tendon sliced, He is Later seen standing on it.
In the scene with the old man, when he loads the shot gun it makes the sound of a pump action shot gun when it is clearly a hammer action.
When the school principal is making a jack o' lantern with the bully, the knife makes the sound of brushing against metal, which wouldn't happen while making a jack o' lantern.